Frederick William Victor Augustus Ernest (German: Friedrich Wilhelm Victor August Ernst) (6 May1882 – 20 July1951) of the House of Hohenzollern was the last Crown Prince of the Kingdom of Prussia and the German Empire. He was colloquially known as William or Wilhelm.

William was born in the Marble Palace of Potsdam in the Province of Brandenburg. He was the eldest son of William II, German Emperor (1859-1941) and his first wife Princess Augusta Viktoria of Schleswig-Holstein (1858-1921).As a young man, the Crown Prince grew up within militaristic circles. He had received little command experience when he was given charge of the 5th Army in August 1914, shortly after the outbreak of World War I. He led this Army until November 1916, and his command included the period of the Verdun Offensive. Since April 1916 he tried in vain to convince the supreme command that the battle no longer made any sense. Only on September 2 was his wish fulfilled.After the outbreak of the German Revolution in 1918, both Emperor William II and the Crown Prince signed the document of abdication. The Crown Prince went into exile to the isle of Wieringen, in the Netherlands. In 1923, he returned to Germany after giving assurances that he would no longer engage in politics. The former Crown Prince held some political ambitions, and was reportedly interested in the idea of running for Reichspräsident as the right-wing candidate opposed to Paul von Hindenburg in 1932, until his father forbade the idea.The Crown Prince supported Hitler for some time, hoping and announcing in public that this man would do for Germany what Mussolini had done for Italy - making an end to all Bolshevist/Marxist influence. He had connections with some organizations, more than loosely connected with the National Socialist Party (Nazi Party) and allowed himself to be used by the Nazi government in various symbolic actions. After the murder of his friend, the former Chancellor Kurt von Schleicher in the Night of the Long Knives (1934), he retreated from all political activities. Most of his efforts from 1919 until 1934 had been directed to make a return of the Hohenzollerns to the throne viable option again, and he had assumed that Hitler would give this idea his support.William lived as a private citizen on his family's estates throughout World War II. Upon his father's death in 1941, William succeeded him as head of the House of Hohenzollern, the former German imperial dynasty. In 1951, the former Crown Prince died of a heart attack in Hechingen, in the ancestral lands of his family in Swabia, as the family's estates in Brandenburg had been occupied by the Soviet Union.

Duchess Cecilie Auguste Marie of Mecklenburg-Schwerin (20 September1886 at Schwerin, Germany - 6 May1954 at Bad Kissingen, Germany) was the wife of German Crown Prince William, the son of German Emperor William II.She was the daughter of Grand Duke Frederick Francis III of Mecklenburg-Schwerin and Grand Duchess Anastasia Mikhailovna of Russia.Duchess Cecilie married William on 6 June 1905 in Berlin. Once she was married she was styled Her Imperial and Royal Highness The German Crown Princess and was also Crown Princess of Prussia.